Oil-extended vi improvers

ABSTRACT

AN OIL-EXTENDED VI IMPROVER WHICH BY OUTWARD APPEARANCE IS DRY COMPRISING (A) 40-60 WEIGHT PERCENT HYDROGENATED BUTADIENCE-STYRENE POLYMER AND (B) 60-40 WEIGHT PERCENT OF A PARAFFINC OIL. THE OIL-EXTENDED VI IMPROVER CAN BE READILY DISPERESED IN A LUBRICATING OIL FOLLOWING STORAGE AND/OR SHIPPING TO PLACE OF UTILIZATION.

United States Patent Ofice 3,630,905 OIL-EXTENDED VI IMPROVERS Poznan M.Sorgo, Bartlesville, Okla, assignor to Phillips Petroleum Company NoDrawing. Filed Nov. 19, 1968, Ser. No. 777,190 Int. Cl. 08d /00 U.S. Cl.260-851 5 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTIONThis invention relates to improved lubricating oils, particularlymineral lubricating oils, and processes of preparing the same. Inaccordance with another aspect, this invention relates to the additionof a lubricating oil in defined amounts to a hydrogenated randombutadiene-styrene copolymer to produce a storable-dry-appearing productwhich can be subsequently dispersed in a lubricating oil to produceformulations that are shear-stable and have a high viscosity index (VI).In accordance with a further aspect, this invention relates tohydrogenated random butadiene-styrene copolymers having defined amountsof butadiene and styrene which are blended with paraflinic oils incontrolled amounts to produce an oil-containing VI improver which byoutward appearance is dry which, subsequent to shipping and/or storage,can be readily dispersed in a lubricating oil.

As is well known, the viscosity of lubricating oils varies with thetemperature. Many oils must be employed over a wide temperature range,e.g., 0 F. to 300 'F., and it is important that the oil not be tooviscous at low temperatures nor too thin at high temperatures. Variationof the viscosity-temperature relationship of an oil is indicated by thewell-known viscosity index value. The higher the viscosity index, theless the change in viscosity with change in temperature. Viscosity at210 F. and at 100 F. is used to determine the viscosity index.

Many attempts have been made to improve the properties, particularly theviscosity-temperature relationships and shear stability of lubricatingoils. It has been proposed to add various materials to the lubricatingoils for this purpose, among which are high molecular weight hydrocarbonmaterials, e.g., polymerized isobutylene, hydrogenated rubber,unvulcanized rubber, and the like. These additives have met with somesuccess, but have solubility problems which result in too low a 210 F.viscosity and too low a viscosity index. Additionally, difficulties havebeen experienced in the time required to disperse some of these VIimprovers into a lubricating oil for subsequent use. It would be highlydesirable to provide a VI improver which can be readily stored for longperiods of time and subsequently shipped to a place of utilization forincorporating at the place of utilization into a lubricating oilcomposition with a minimum of effort and time for effecting thedispersion.

In accordance with the invention, it has been discovered thatoil-extended hydrogenated butadiene-styrene VI improvers can be readilyand eifectively incorporated by dis-- persing in lube oils subsequent toextended periods of storage and/ or times involved in shipping from oneplace to another.

readily dispersible' oil-extended VI improver.-

3,630,905 Patented Dec. 28, 1971 A further object of this invention isto provide new and improved lubricating oils and methods for preparingthe same.

Another object of this invention is to improve mineral and lubricatingoils by adding specific hydrogenated random rubbery copolymers thereto.

A further object of this invention is to provide a method for preparingan oil-extended VI improver which can be readily stored for long periodsof time and subsequently dispersed into a lubricating oil.

Other aspects and objects, as Well as the several advantages of theinvention, will be apparent to those skilled in the art upon furtherstudy of the specification and appended claims.

SUMMARY OF THE INVENTION In accordance with the invention, anoil-extended VI improver is provided comprising 40-60 weight percent ofa hydrogenated random butadiene-styrene copolymer and 60-40 weightpercent of a parafiinic oil.

Further, in accordance with the invention, the hydrogenated randombutadiene-styrene copolymer blended with the parafiinc oil has abutadiene content of 30-44 weight percent.

A presently preferred composition comprises 50 weight percenthydrogenated butadiene-styrene rubber polymer and 50 weight percent of aparalfinic oil.

In accordance with a further embodiment of the invention, the method ofproviding a readily dispersible VI improver is provided comprisingforming an oil-extended composition by blending together 40-60 weightpercent of a hydrogenated butadiene-styrene VI improver and 60- 40weight percent of a paraffinic oil and either prior to or subsequent tostorage and/or shipping dispersing the oilextended VI improvercomposition with a lubricating oil in an amount suflicient to form alubricating oil composition containing up to 20 weight percent polymer.

At present, the oil-extended additives, which have an appearance,externally at least, of being dry and a solid, are usually employed inan amount in the approximate range of 0.5 to 20 weight percent polymerand a lubricating oil, preferably 1 to 15 weight percent polymer in thefinal lubricating oil composition. One skilled in the art in possessionof this disclosure, having studied the same, can routinely determine theoptimum proportion of copolymer for his purpose.

The copolymers or additives of the present invention have a molecularweight in the approximate range of 25,000 to 125,000, a now preferredrange being from about 30,000 to about 75,000. The copolymer can be onecontaining from about 30 to about 44 parts by weight butadiene per 100parts by weight of total monomers. The values for butadiene content ofthe polymers are actually those for the butadiene in the monomerscharge. However, these values are very close to those for the butadienecontent of the polymers because essentially complete conversion wasobtained in all polymer synthesis runs. The copolymers have a vinylcontent before hydrogenation of less than 35 weight percent. Duringhydrogenation, olefinic group hydrogenation is weight percent or moreand phenyl group hydrogenation is 5 weight percent or less.

The molecular weights given throughout this application was calculatedfrom the amount of initiator used in preparing the polymers, with anallowance for the known scavenger level. These values, known as kineticmolecular weight values, are within experimental error, the same asnumber average molecular weights [see Journal of Polymer Science, PartA, vol. 3, page 191 (1965)],

The copolymers of the present invention presently preferred can beprepared by any of the conventional techniquesknown in the art, such asthose described in US. Pat. 2,975,160, R. P. Zelinski, issued Mar. 14,1961. For

example, a mixture of butadiene and styrene monomers can be polymerizedusing butyllithium as a catalyst and tetrahydrofuran as a randomizingagent. The hydrogenation can be carried out in any manner known in theart, such as by the process of U.S. Pat. 2,864,809, R. V. Jones et al.,issued Dec. 16, 1958, or that of US. Pat. 3,113,986, D. S. Breslow etal., issued Dec. 10, 1963, or that of US. Pat. 3,205,278, S. J.Lapporte, issued Sept. 7, 1965. For example, the copolymer can behydrogenated over a reduced nickel-kieselguhr catalyst or over a nickeloctoatetriethylaluminum catalyst system. The hydrogenatedbutadiene-styrene copolymers of the present invention are polymers whichhave been sufficiently hydrogenated to remove substantially all of theolefinic unsaturation, leav ing only the aromatic (i.e., phenyl group)unsaturation.

The extent of hydrogenation of the olefinic bonds and of the phenylgroups in the butadiene-styrene random copolymers was determined byinfrared analysis before and after hydrogenation.

The parafiinic oils added as extender oils for the hy- H drogenatedbutadiene-styrene polymer are paraflinic oils of the nature of andcompatible with lube oils. These parafiinic oils normally have amolecular weight in the range of 325 to 400 and a stable viscosity at100 F. in the range of 90 to 125 SUS. A typical example of suchparaffinic oils is Pennsylvania petroleum.

In actual operation, the oil-extended hydrogenated butadiene-styrene VIimprover of the invention can be prepared by blending together a rubberypolymer and a paraffinic oil in the amount set forth above under thefollowing conditions:

Method A: The rubbery polymer is heated to about 300 F. and theparafiinic oil is added with stirring, to give a uniform mixture. Uponcooling to room temperature, a slightly tacky solid is obtained in whichthe 011 is uniformly dispersed.

Method B: The rubbery polymer dissolved m a solvent such as cyclohexane(about 14 percent solids) is mixed with the paraffinic oil, and then thesolvent is removed by steam stripping, and the oil-extended polymer isovendried.

The oil-extended additives thus prepared yields a product which byoutward appearance is dry. This oil-extended additive can beconveniently stored for extended periods of time or shipped immediatelyor after storage to a place of utilization. Subsequently, when it isdesired to mix the oil-extended hydrogenated butadiene-styreneVI1mprover with a lubricating oil this can be accomplished by conventionaltechniques.

In the preparation of the lubricating compositions, various mineral oilsare employed. Generally, these are petroleum origin and are complexmixtures of many hydrocarbon compounds. Preferably, the mineral oils arerefined products such as are obtained by well-known refining processes,such as by hydrogenation, by polymerization, by dewaxing, etc.Frequently, the 0118 have a Saybolt viscosity at 100 F. in the range ofabout 60 to 5,000, and a Saybolt viscosity at 210 F. of about 30 to 250.The 0118 can be of paratfinic, naphthenic, or aromatic types, as well asmixtures of one or more types. However, the additives of the inventionhave special advantages when employed with parafiinic types of oils suchas are obtained by solvent extraction of a suitable refinery stream.Many suitable lubricating compositions are available as commercialproducts, such as those used as motor oils, gear oils, automatictransmission oils, and the like.

The final lubricating compositions of the invention can comprise one ormore of other additives known to those skilled in the art, such asanti-oxidant, pour point depressants, dyes, detergents, etc.

EXAMPLE I An oil-extended hydrogenated butadiene-styrene VI improver wasprepared by blending together 40 percent polymer and 60 percent of aparafiinic oil.

The hydrogenated polymer used in this example was a solution-polymerizedrandom butadiene-styrene copolymer having a molecular weight of about50,000, and was prepared using the following recipe and conditions:

Parts by weight Butadiene 35 Styrene 65 Cyclohexane 800 Tetrahydrofuran1.5 sec-Butyllithium 0.154 Initiation temperature, "F 122 Initiationpressure, p.s.i.g

Charge order was cyclohexane, reactor purged with nitrogen, butadiene,styrene, tetrahydrofuran, and sec-butyllithium. Essentially quantitativeconversion was obtained in 3 hours. At that time the unterminatedproduct was transferred to a hydrogenation reactor, 0.13 g. of nickel(as nickel octoate) and 1.05 g. of triethylaluminum in cyclohexane wereadded, the reactor was pressured to 50 p.s.i.g. with hydrogen, thetemperature was increased slowly to 350 F., the hydrogen pressure wasincreased to 400 p.s.i.g., and the temperature rose quickly to 395 F.and fell to 350 F. in about minutes. Reaction was continued for 1.5hours at 350 F. and 400 p.s.i.g., the reactor was cooled to 170 F., andthe essentially completely hydrogenated polymer was recovered. Withrespect to the polymers in this and succeeding examples, essentiallycompletely hydrogenated means that 95 weight percent or more of theolefinic groups are hydrogenated and 5 weight percent or less of thephenyl groups (when present) are hydrogenated. The polymers of theinvention in this and succeeding examples all contained less than weightpercent vinyl unsaturation before hydrogenation.

The paraffinic oil had the following properties:

API gravity 32.9 Flash point, F 390 Viscosity, SUS at 100 F 98.2Viscosity, SUS at 210 F 39.3 Viscosity index 101 Pour point, F +5 Carbonresidue nil Color, ASTM 1 The materials used in the example above weremade by mixing the paraflinic oil with the cyclohexane solution ofpolymer (about 14 percent solids) followed by steam stripping to removecyclohexane solvent and then oven drying the oil-extended additive. Theoil-containing VI improver, following drying, is a solid that can bereadily stored and/or shipped to a place of utilization.

The oil-extended hydrogenated butadiene-styrene VI improver formed abovepercent polymerpercent parafiinic oil) was subsequently added tosufiicient lubrieating oil at 300 F. to produce an additive packagecontaining 15 weight percent polymer. The polymer went into solutioninto the lubricating oil in about 10 minutes with stirring.

Solution of polymer crumb at 300 F. takes about 20 minutes and solutionof compacted polymer takes considerably longer, demonstrating a markedimprovement of dissolution of polymer using the oil-extended polymeraccording to the invention.

EXAMPLE II A control run was carried out whereby an oil-extendedhydrogenated butadiene-styrene VI improver prepared colntaining percentpolymer and 25 percent paraflinic o1 The oil-extended VI improver (75percent polymer-25 percent oil) was added to a lubricating oil at 300 F.in an amount sufiicient to make an additive package containing 15 weightpercent polymer. In this example, 40 g. of a glob (cut into pieces) ofthe 75 percent polymer-25 percent oil was added at 300 F. to thelubricating stuck.

Solution of the oil-extended VI improver was not complete in 40 minutesof stirring.

It can be seen from this example that there was insufficient paraflinicoil in the oil-extended VI improver and that the results were evenpoorer than a control with no oil.

EXAMPLE III In another run, a 50-50 polymer-oil-extended hydrogenatedbutadiene-styrene VI improver was prepared. The butadiene-styrene rubberand paraffinic oil were the same materials as employed in the previousexamples.

The oil-extended hydrogenated butadiene-styrene VI improver wasdissolved in 4 minutes in enough lubricating oil to make a final 50percent solution of polymer (weight percent). The temperature of theefiecting solution of the oil-extended polymer was 300 F The 50-50composition is a somewhat tacky solid exhibiting no cold flow whichconstitutes a very desirable product to sell and use as an additive forlubricating oils.

I claim:

1. A solid, substantially dry appearing, oil dispersible viscosity indeximprover composition consisting essentially of (a) 40-60 Weight percentof a hydrogenated random butadiene-styrene rubbery copolymer having abutadiene content of 30-44 weight percent and the remainder beingstyrene, and (b) 60-40 weight percent of a parafiinic oil.

2. A composition according to claim 1 wherein the 6 hydrogenated randombutadiene-styrenc copolymer has a molecular weight in the range of25,000-125,000.

3. A composition according to claim 1 wherein said copolymer issubstantially free of all olefinic unsaturation.

4. A composition according to claim 1 wherein (a) comprises percent ofsaid composition and (b) comprises 50 percent of said composition.

5. A composition according to claim 1 wherein the oilextended viscosityindex improver composition of (a) and (b) are combined with alubricating oil in an amount sufiicient to form a final lubricating oilcomposition having a viscosity index of at least and the amount of (a)present in said composition being in the range of 0.5 to 20 weightpercent.

References Cited UNITED STATES PATENTS 3,305,516 2/1967 Smith 26033.63,307,605 3/1967 Bulgin et a1. 152330 3,479,313 11/1969 Kreider 26029.73,485,787 12/1969 I-Iaefele et a1. 26033.6

JOSEPH SCHOFER, Primary Examiner R. A. GAITHER, Assistant Examiner US.Cl. X.R.

